daibaan

this may not be a power supply problem at all!

When I first got my OBi, I have the following connections: LINE, PHONE, ETHERNET, POWER.
- a phone is connected to the PHONE port directly.
- LINE port is connected the red/green paire of wire from the outside phone panel
I play with it for a week, make sure I have all the basics figured out. No AC hum problem.

Then I connect the PHONE port to the second pair (yellow/black) of my house wire, basically route the OBi phone port back to the phone connect panel outside of my house, which is connected to my 4 other locations in my house. that is when I start hearing the AC hum.  Only one of these 4 locations actually has a phone connection to the yellow/black pair of wire, at the other 3 locations the phones are still connected to the red/green pair and the yellow/back pair is left dangling, which I assume acts as antennae packing AC hum.  As soon as I disconnected the 3 yellow/black pairs from my connection panel, the AC hum is gone.

So, before blaming AC hum on the power supply, check to see if the problem exist when
- phone is directly connected to the phone company line (i.e w/o OBi in place)
- phone is directly connected to the OBi phone port

daibaan

Yes, I have seen the power-supply related AC hum problem mention in obitalk forum, and suggestion on using other un-certified power supply.

I am just sharing my experience of non-power-supply related AC hum problem in case someone encounter the same situation